The Scent of a Woman

Don't trust the hype about pheromones and sexual attraction.

The notion that our body odors are potent, chemically charged mating signals—so-called pheromones—is so pervasive in women's magazines and websites, you would think that all you need is one good sweat to lure your guy. This spring, Shape magazine proclaimed thatworking out together fires up a relationship, because when you're hot and sweaty, "you continue to release attraction-boosting pheromones for an hour after you finish exercising." Want to turn an ordinary dinner date into "incredibly hot sex"? All you have to do, according YourTango, a love-advice website, is avoid putting perfume on your neck, breasts, or genitals, because that "hides the important pheromones that drive men wild." Last year, Cosmopolitan—another go-to source for medically oriented dating strategies—suggested you go panty-free so that the "odors in your pheromones—that natural chemical you emit that attracts men—may more easily waft into the air to be picked up subliminally by the primitive part of his brain."

If only it were so. Pheromones, in scientific parlance, are aromatic chemicals emitted by one member of a species that affect another member of the same species, either by altering its hormones or by compelling it to change its behavior. When they work, they are truly bewitching. For instance, when a female silkworm moth wants to get her guy, she sprays a chemical called bombykol from her abdominal gland and her targeted male transforms into a sex slave, trailing the scent until he mounts her. It's an enviable feat. Still, it's a big leap to extrapolate from bugs to people—or even to lab mice, for that matter. No scientific study has ever proven conclusively that mammals have pheromones.

"The whole pheromone thing got picked up by the mass media," says Richard Doty, director of the University of Pennsylvania's Smell and Taste Research Center and author of The Great Pheromone Myth. It feeds into our need to believe, he said, that there "is all this subliminal stuff going on that is affecting us—who we mate with, who we want to be with. It's this mythical perspective." And marketers, like women's magazines, are only too happy to exploit that myth. That's how a whole junk-science industry of pheromone-perfumes, pheromone-soaps, and pheromone-cosmetics managed to spring up from a strange menagerie of misconstrued mammal studies.

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About 50 years ago, Richard Michaels, an English psychiatrist and primate researcher, claimed to have found chemicals in the vaginas of rhesus monkeys that attracted males of the species. He and his colleagues called the substances copulins, as in "copulate." Soon thereafter, Michaels released a patented copulins recipe—a blend of vaginal aliphatic acids, based on the monkey secretions—which has since become the basis for most women's perfumes and soaps that claim to include "pheromones" that attract the opposite (human) sex.

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But even Michaels realized that the sense of smell might only be a minor factor in mate selection. In a subsequent study, published in the Journal of Endocrinology in 1982, he paired a dozen male rhesus monkeys with four females apiece. Some of the females had copulins rubbed on their vaginas; some had placebo. Researchers then counted how many times each female was mounted. All the females had their ovaries removed, to wipe out the effects of natural hormones that could confound results, and were given estrogen, thought to enhance the actions of copulins. Still, the study found that the vast majority of males were not influenced by copulins. In fact, they were more often swayed by the presence of a dominant female than by smell alone. (The alpha female would literally block the male's access to the other three monkeys.) Meanwhile, the few human studies on the topic have tried to determine whether male volunteers wearing surgical masks coated with lab-made copulins were more aroused by photos of women than were volunteers wearing placebo-coated masks. They weren't.

The other so-called human pheromone that shows up in body care products is androstenedione, a chemical found in sweat. Androstenedione has been making the media rounds for years. Initial research in the early 1990s suggested that women were aroused by its musky smell, but later studies complicated that notion. One famous study from 1995—in which women were asked to sniff a bunch of sweaty T-shirts and choose the one they found most appealing—suggested that it wasn't the chemical itself that attracted women, but the way it mixed with a man's genes. (The women tended to choose T-shirts from men whose immune systems were most different from their own, suggesting that humans have an innate smell-based system to avoid mating with siblings.)

In 2007, astrostenedione's reputation as a scientific seduction tool should have crumbled even further: That's when Andreas Keller, a geneticist at Rockefeller University, discovered (subscription required) that, depending on the particular variation of the olfactory gene OR7D4 you possess, you may find androstenedione pleasantly floral, you may find it utterly repulsive, or you may not be able to smell it at all.

A true human pheromone would have universal appeal across the species. But the latest research on olfaction hints that our smell systems are much more individualized than we ever imagined. Scientists now estimate that humans have roughly 350 working olfactory genes, which may vary from person to person. Considering that spread, the idea of a truly effective bottled aphrodisiac seems silly—or as Rachel Herz, a Brown University psychologist and author of The Scent of Desire,calls it, a "commercial fantasy."

None of this is to say that smells aren't powerful. Who doesn't get hungry from the smell of home-baked chocolate chip cookies? Maybe your guy's cologne is a real turn-on. But there's a huge difference between an instinctual behavior-changer and a pleasing odor. Besides, most of the evidence nowadays suggests that the way we react to aromas is learned—learning that can go back to the womb. For instance, Doty refers to a 2004 study on sheep that interrogated the long-held assumption that females ovulate in the presence of males, most likely due to pheromones. The researchers put lavender on the males and after a few mating sessions, the females began ovulating from the scent of lavender alone. The findings suggest that the females' hormonal response was an acquired behavior, rather than an innate one.

This shift in thinking is really quite liberating. It means, for one thing, that we may have more complicated relationships with our men than a female silkworm moth has with hers. It also means that we're not programmed to respond in one particular way but that we can learn—indeed, train ourselves—to respond to an odor the way we want to. Pamela Dalton, a scientist at the Monell Chemical Senses Center in Philadelphia, practices something she calls "pairing," or marrying an odor to a particular emotional state. She buys a new fragrance every time she goes on vacation so that when she returns to work, one spray puts her back in holiday mode. We may never be able to lure that gorgeous stranger with a one-size-fits-all fragrance, but perhaps we can train our lovers to respond to us more passionately by wearing a new perfume on a romantic night out. Later, one whiff of the scent will tug at his odor memory and he'll be back to us like a moth to a flame—I mean, like a male silkworm moth to bombykol.